Removal of astringency in persimmon fruits (Diospyros kaki) subjected to different freezing temperature treatments

The effects of two different freezing temperatures (- 20 degrees C and - 80 degrees C) on the astringency trait of persimmon fruits during 15 to 60 days of storage were investigated. The levels of soluble and insoluble tannins, proanthocyanidins and other physicochemical characteristics were evaluated. Storage at - 20 degrees C and - 80 degrees C temperatures up to 60 days has been found to be an effective method to remove astringency of persimmon fruits. Proanthocyanidin concentration was negligible at both temperatures during storage. Total soluble solid contents were decreased as 3.34 from 4.59 (mg/g DW) whereas, insoluble tannin contents were increased as 20.30 from 16.45 (mg/g DW) by freezing temperatures treatment during storage. Comparatively, higher soluble tannin content 11.68 (mg/g DW) and lower insoluble tannin content 10.02 (mg/g DW) was observed in control (day 0). Therefore, the astringency of persimmon fruits incubated at - 20 degrees C and - 80 degrees C was markedly reduced and after 15 up to 60 days of storage, the astringent taste virtually disappeared. The proanthocyanidin contents were decreased as 0.02 from 0.52 (mg/g DW) at - 20 degrees C storage and 0.17 from 0.47 (mg/g DW) at - 80 degrees C storage, in comparison with the control 2.65 (mg/g DW). The moreover, along with the removal of astringency, other physicochemical parameters including color, pH, moisture content, total soluble solid, and sensory attributes were also conserved on freezing at both the temperatures. These findings suggest that freezing temperature treatments aid the removal of astringency from persimmon fruits which could be used in different food preparations or as supplements.

Automated summary

The study found that storage at -20 degrees C and -80 degrees C for up to 60 days effectively removes the astringency of persimmon fruits by decreasing proanthocyanidin concentration and altering tannin contents. The removal of astringency was accompanied by preservation of other physicochemical parameters during freezing. These findings suggest that freezing temperature treatments can aid in the removal of astringency from persimmon fruits, making them suitable for various food preparations or supplements.